The invention is based on an articulation connection or link joint.
Link joints are frequently used in lever linkages, including wiper drives, especially in so-called four-bar linkage wiper drive installations. In this respect, a first lever, e.g., a fastening part, is usually constructed as a bent sheet metal part having, at the end on the joint side, a trough whose edge is bent outward at the free sides in the direction of the bottom of the trough in the shape of an apron or skirt and projects over the base of the trough. A bearing pin is riveted in the center of the trough accompanied by an outer washer, wherein a rivet part is formed integral with the bearing pin and the rivet head is covered by a protective cap which is fastened to the washer. The bearing pin is enclosed by a bearing eye of a second lever, e.g., a coupling lever, in which a bearing part of plastic is injected. The second lever is held axially between a bearing disk in the trough of the first lever and a collar of the bearing journal. The bearing between the bearing pin and the bearing part is sealed outwardly. The second lever carries an outer covering in the area of the bearing eye.
The wiper drives which are arranged in the area between a vehicle windshield and a part of the body, particularly an engine hood, substantially determine with their link joints the distance between the body part and the windshield, wherein this distance should be kept as short as possible for visual and acoustic reasons as well as for reasons of flow.
According to the invention, the bearing pin has a hollow space which is open at least toward one front side. This saves on material and weight on the one hand and, on the other hand, numerous possibilities are opened for constructing the link joint in a simpler and especially in a flatter manner in that the hollow space is utilized for the connection between the bearing pin and the first lever.
According to a construction of the invention, the trough has, in the center, a deep-drawn or cupped hollow body which projects into the hollow space of the bearing pin and is riveted at its front side with the bearing pin. The hollow body which is formed integral with the first lever can serve to fasten the bearing journal in the manner of a hollow rivet, but can also form the bearing journal by itself. In both cases, with the length of the bearing surface remaining the same, the link joint is flatter because, in the first case, the connection point between the first lever and the bearing pin lies within the joint and therefore does not take up any axial construction space and, in the second case, a connection point is omitted. An outer washer and protective cap can be dispensed with. This facilitates manufacture and assembly and reduces weight and use of material. Further, the connection point is located in an area with low mechanical loading with respect to bending moments.
Since the bottom of the trough forms the lower limit of the first lever, the skirt-shaped part of the trough edge which previously concealed the washer and protective cap can also be dispensed with. The trough edge advisably runs in a quarter circle transverse to a swivel axis and terminates radially with a joint cover at the second lever. The diameter of the bearing eye with its covering accordingly determines the greatest width of the lever which is reduced compared with conventional link joints.
The hollow body can be open or closed. When closed, it is no longer necessary to seal relative to the joint space. The hollow body can only project slightly into the hollow space of the bearing pin and can rest against a corresponding narrowed portion of the hollow space by its riveted head. In another construction, the hollow body is guided through the hollow space and is riveted at its free end with a collarless bearing journal via a bearing disk. In this case, the bearing journal is formed of a cylindrical spacer sleeve which is held between the two bearing disks. The hollow body is connected with the outer bearing disk in that its outer edge is beaded and the bearing disk presses against the end face of the spacer sleeve or its base is connected with the bearing disk by a separate rivet. According to another construction of the invention, the hollow body forms a collar at the front side for contact by the bearing disk, wherein the bearing disk is riveted against this collar with the outer part of the hollow body.
The height of the link joint can be further reduced through the use of a high-quality bearing bush, e.g., formed of plastic-coated steel, which is connected with the bearing pin or the bearing part. The length of the bearing surface and friction are reduced by the increased loading capacity and wear behavior is also improved.
When the hollow body itself serves as a bearing journal, a bearing material is preferably sprayed or injection-molded onto its outer circumference. The layer of bearing material extends up to the trough base. In this construction, the hollow body carries the second bearing disk at a collar, against which it is riveted with the edge of the hollow body.
The link joint can be constructed in a more economical manner even when the second lever is formed by a bent sheet metal part which has a substantially U-shaped cross section and has everted portions facing inward in the area of the link joint, wherein the bearing part is injection-molded on the everted portions on both sides. Owing to the injection on both sides, the everted portions do not deform during the injection process and the bearing surfaces can be produced within the desired tolerances. In order to promote the injection process, it is further advisable to more or less fill up the intermediate space between the everted portion and the U-shaped profile.
The U-shaped profile is lined with a plastic covering. When the covering closes the open side of the U-shaped profile, a lever is formed which is closed on all sides. The advantages of the second lever as a bent sheet metal part are so great that it appears worthwhile to utilize it not only in combination with a link joint according to the invention, but also with a link joint according to the preamble of claim 1.